This study will test a new medication strategy designed to help smokers quit. It will evaluate Baclofen, a drug currently approved and available in Canada as a myorelaxant. Forty five nicotine-dependent smokers will enroll in this study. Fifteen will receive placebo (inactive pill), fifteen will receive baclofen 30 mg/day, and fifteen will receive baclofen 60 mg/day. Once enrolled, subjects will visit CAMH on a weekly basis for assessment of smoking behaviour, a brief health check (vitals, BP and AE screening), delivery of brief individual smoking cessation counselling, and collection of breath, blood and urine samples (as scheduled) to a) measure levels of nicotine and its metabolites, b) conduct pregnancy and tox testing. The medication phase of this study lasts 12 weeks. Two follow-up visits will be scheduled at week 13 and at six months after trial completion.